27,514 research outputs found
Thermal treatment of superconductor thin film of the BSCCO system using domestic microwave oven
In this work, we report the preparation of a superconductor thin film of the
BSCCO system using a good quality powder with nominal composition
Bi_{1.8}Pb_{0.4}Sr_2CaCu_2O_x which was thermally treated using a domestic
microwave oven (2.45 GHz, 800 W). This film was grew on a single crystal of
LaAlO_3(100) substrate and exhibited a crystalline structure with the c-axis
perpendicular to the plane of the substrate. An onset superconducting
transition temperature was measured at 80 K.Comment: 4 pages, 5 figure
Beam alignment techniques based on the current multiplication effect in photoconductors Third summary technical progress report, 15 Nov. 1966 - 15 Oct. 1967
Beam alignment techniques developed for infrared sensitive single crystal germanium to study multiplication effect in photoconductor
On central tendency and dispersion measures for intervals and hypercubes
The uncertainty or the variability of the data may be treated by considering,
rather than a single value for each data, the interval of values in which it
may fall. This paper studies the derivation of basic description statistics for
interval-valued datasets. We propose a geometrical approach in the
determination of summary statistics (central tendency and dispersion measures)
for interval-valued variables
Magnetic phases evolution in the LaMn1-xFexO3+y system
We have investigated the crystal structure and magnetic properties for
polycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0,
prepared by solid state reaction in air. All samples show the ORT-2
orthorhombic structure that suppresses the Jahn-Teller distortion, thus
favoring a ferromagnetic (FM) superexchange (SE) interaction between
Mn^{3+}-O-Mn^{3+}. For x=0.0 the oxygen excess (y ~ 0.09) produces vacancies in
the La and Mn sites and generates a fraction around 18% of Mn^{4+} ions and 82%
of the usual Mn^{3+} ions, with possible double exchange interaction between
them. The Fe doping in this system is known to produce only stable Fe^{3+}
ions. We find an evolution from a fairly strong FM phase with a Curie
temperature T_{C} ~ 160 K, for x=0.0, to an antiferromagnetic (AFM) phase with
T_{N} = 790 K, for x=1.0, accompanied by clear signatures of a cluster-glass
behavior. For intermediate Fe contents a mixed-phase state occurs, with a
gradual decrease (increase) of the FM (AFM) phase, accompanied by a systematic
transition broadening for 0.2 < x < 0.7. A model based on the expected exchange
interaction among the various magnetic-ion types, accounts very well for the
saturation-magnetization dependence on Fe doping.Comment: 27 pages, 9 figure
Random attractors for degenerate stochastic partial differential equations
We prove the existence of random attractors for a large class of degenerate
stochastic partial differential equations (SPDE) perturbed by joint additive
Wiener noise and real, linear multiplicative Brownian noise, assuming only the
standard assumptions of the variational approach to SPDE with compact
embeddings in the associated Gelfand triple. This allows spatially much rougher
noise than in known results. The approach is based on a construction of
strictly stationary solutions to related strongly monotone SPDE. Applications
include stochastic generalized porous media equations, stochastic generalized
degenerate p-Laplace equations and stochastic reaction diffusion equations. For
perturbed, degenerate p-Laplace equations we prove that the deterministic,
infinite dimensional attractor collapses to a single random point if enough
noise is added.Comment: 34 pages; The final publication is available at
http://link.springer.com/article/10.1007%2Fs10884-013-9294-
Improving the Knowledge on Seismogenic Sources in the Lower Tagus Valley for Seismic Hazard Purposes
The Lower Tagus Valley, that includes the metropolitan area of Lisbon, has been struck by several earthquakes which produced significant material damage and loss of lives. Their exact location remains unknown. Our goal is to shed some light into the seismogenic sources in the area using seismic reflection and geological data. In areas with no seismic coverage, potential-field data interpretation was carried out. Seismicity was overlaid to the potential seismogenic structures and high-resolution data was acquired in order to confirm which structures have been active into the Quaternary. Three major fault-zones affecting the Neogene were identified: V. F. Xira, Samora-Alcochete and Pinhal Novo. For the first fault, strong evidences suggest it is active. The other two fault-zones and other structures previously unknown can be correlated with several epicentres. Empirical relationships between maximum moment magnitude and fault area indicate that MW > 6.5 earthquakes can be expected for the larger structures
Triagem de Bibliotecas Metagenômicas para Isolamento de Clones com Atividade de Celobiohidrolase.
Topological insulator particles as optically induced oscillators: towards dynamical force measurements and optical rheology
We report the first experimental study upon the optical trapping and
manipulation of topological insulator (TI) particles. By virtue of the unique
TI properties, which have a conducting surface and an insulating bulk, the
particles present a peculiar behaviour in the presence of a single laser beam
optical tweezers: they oscillate in a plane perpendicular to the direction of
the laser propagation, as a result of the competition between radiation
pressure and gradient forces. In other words, TI particles behave as optically
induced oscillators, allowing dynamical measurements with unprecedented
simplicity and purely optical control. Actually, optical rheology of soft
matter interfaces and biological membranes, as well as dynamical force
measurements in macromolecules and biopolymers, may be quoted as feasible
possibilities for the near future.Comment: 6 pages, 5 figures. Correspondence and requests for Supplementary
Material should be addressed to [email protected]
Desempenho da fase adulta de Chysoperla externa (Hagen, 1861) (Neuroptera; Chrysopidae) utilizando dietas artificiais.
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